1. Field of the Invention
The present invention relates to an eccentric shaft of a rotary piston internal combustion engine of trochoidal type of construction with a fluid-cooled housing with a multi-arc casing runway surfacing, of which the side walls have an eccentric shaft passing therethrough. Pistons are mounted and journalled rotating upon an eccentric or eccentrics of the eccentric shaft and these pistons have planetary-type rotation with corners of the pistons in continuous engagement along the casing runway surfacing. An eccentric bearing means for the pistons on the eccentrics of the eccentric shaft are cooled by a cooling medium branched off via a bypass of the cooling system of the housing and conveyed via hollow spaces or chambers in the eccentric shaft and in the eccentric means.
A purpose of such formation or construction of the eccentric shaft is to cool the eccentric bearing not as previously via the piston but rather directly.
2. Description of the Prior Art
An eccentric shaft constructed hollow for a rotary piston internal combustion engine is described in a copending U.S. application Ser. No. 876,197-Eiermann filed June 19, 1986 and belonging to the assignee of the present invention as based upon a German application Ser. No. P 35 45 820.8 (PW 49). Fluid or liquid cooling medium is supplied via a bypass of the housing cooling system through a hollow chamber of the eccentric shaft and through a pipe or tube concentric to the eccentric shaft, preferably rotating with the eccentric shaft and this cooling medium is carried away again in an annular space or chamber around this pipe or tube. In that way, the eccentric bearing can be cooled directly so that an indirect cooling via the piston with oil, mixture or suctioned air no longer is required. The cooling of the piston itself, when the piston consists of a good heat-conducting material, for example aluminum, can occur via the housing side walls. A cooling system adapted for such an arrangement is disclosed and described in a copending U.S. patent application Ser. No. 944,808-Eiermann filed Dec. 19, 1986 belonging to the assignee of the present invention and based upon a German application of Ser. No. P 35 45 818.6 (PW 48).
With such hollow shafts there is to be noted that an otherwise unattainable weight reduction of the internal combustion engine can be attained, which however would be justified only for predetermined applications or use situations including for example aircraft engines or portable units that would justify the utilization of special and novel techniques.